During evolution of a communications network toward all Internet Protocol (IP), end-to-end QoS is very important for providing a service that satisfies a customer. An IP network can provide various services (such as video on demand, file downloading, and website browsing). Different services have different requirements for QoS, and charging modes are also different (for example, online charging or offline charging may be adopted, and charging may be performed according to traffic or duration). To solve the foregoing QoS-related problems, the 3rd Generation Partnership Project (3GPP) defines a policy and charging control function (PCC) architecture to meet a requirement for performing different QoS control on different services. A technical specification TS 23.203 defines the PCC architecture. Referring to FIG. 1, functions of the entities are described as follows:
Application function entity (AF): mainly defines a policy and charging control rule for a policy control and charging rules function entity (PCRF), and dynamically provides application layer session information.
PCRF: defines a corresponding policy according to limitations on network access of a user, information about an ongoing application service of the user, configuration made by a local operator, and user subscription information, and provides the policy for a policy and charging enforcement function entity (PCEF) for execution, where the policy includes: service data flow detection, QoS control, gating, flow-based charging, and the like.
PCEF: executes a policy delivered or specified by the PCRF, that is, completes detection of the service data flow, implements QoS guarantee of the service data flow, performs gating, and completes online/offline charging and functions such as triggering a session with a control plane, for example, a gateway GPRS support node (GGSN entity) in a general packet radio service (GPRS).
Functions of interfaces are described as follows:
Rx: is a reference point used by the AF to deliver information related to an application layer session, including an IP filter for identifying the service data flow, bandwidth information required by a service flow, and the like.
Gx: is a reference point used by the PCRF to dynamically control a PCC rule executed by the PCEF, and has the following functions: establishing, maintaining, and terminating an IP-connectivity access network (IP-CAN) session; requesting, by the PCEF, the PCC rule from the PCRF; providing, by the PCRF, the PCC rule for the PCEF; negotiating an IP-CAN bearer establishment mode, and so on.
Currently, with refined operation of data services, a large number of users may subscribe to a user package that controls the QoS based on time. When PCEFs simultaneously execute a QoS update, PCRF or PCEF overload may occur, which may result in update message congestion or system breakdown, or cause a delay in update of the QoS.